Gastric linitis plastica (GLP) is a diffusely infiltrating carcinoma of the stomach that is usually diagnosed in an advanced stage and associated with poor prognosis. Recent studies to evaluate ploidy of these tumors are not conclusive. We undertook a retrospective study of 43 surgically treated patients with GLP (27 males, 16 females, mean age 65 years) to see if ploidy could be used to predict outcome. Flow cytometric DNA analysis was performed on paraffin-embedded tissue using the modified Hedley technique. Mean follow-up interval was 11 months (1-72 months) with 18 (42%) alive at end of study. The remaining 25 (58%) died with a mean survival of 7 months. Lymph node status was positive in 31 (70%) and negative in 12 (30%) of patients. Twenty-nine (67%) of tumors were diploid; 14 (33%) were aneuploid. Statistical analysis revealed overall survival correlated significantly (P = 0.04) only with lymph node status. Diploid tumors had 18 (60%) positive and 11 (40%) negative lymph nodes, whereas aneuploid tumors had 13 (93%) positive and 1 (7%) negative nodes. DNA content correlated significantly (P = 0.05) with lymph node status, but not with overall survival. Tumors with positive lymph nodes were 18 (51%) diploid and 13 (42%) aneuploid; tumors with negative nodes were 11 (92%) diploid and 1 (8%) aneuploid. Conclusions: The majority of GLP tumors manifest diploid characteristics, and the presence or absence of lymph node metastasis is a major determinant in overall survival.